Too old, too expensive and no longer sustainable! The outdoor pool in Grubberg must be closed, the mayor (Gisela Schneeberger) thinks. The opportunity for developer Albert Dengler (Sebastian Bezzel): The vacant area offers plenty of space for new apartments. In return, he would even demolish the old baths free of charge. But the two of them have not reckoned with Karl (Milan Peschel). He is not only the pool attendant, he is the swimming master, the poolside sheriff! He has been for over 30 years and nothing is supposed to change! In order to save the open-air swimming pool, a citizen's petition would be necessary. But where should Karl get the 600 signatures he needs? Not even the few remaining bathers are in favor of him. He constantly clashes with Dr. Rieger (Rick Kavanian) in particular. But he also simply can't manage to jump from the 5-meter tower - and the diving tower isn't a standing tower, after all! Even Sali (Dimitri Abold), the Nigerian trainee lifeguard, is better integrated than Karl, although all he really wants is to get out of Germany as quickly as possible and go to Canada. It's only when Sali meets Lisa (Sarah Mahita), an ex-professional swimmer who secretly does her laps at night in the outdoor pool, that things get complicated. Should he stay in Germany and help Karl? And save Lisa's refuge with the open-air pool?